The present invention relates to an assembly for loading and delivering a stent.
An intraluminary prosthesis is a medical device used in the repair and/or treatment of diseases in various body vessels, for example, a stent. Stents are generally cylindrical shaped devices that are radially expandable to hold open a segment of a blood vessel or other anatomical lumen after implantation into the body lumen. For example, stents may be used in the coronary or peripheral vasculature, esophagus, trachea, bronchi colon, biliary tract, urinary tract, prostate, brain, as well as in a variety of other applications in the body. These devices are implanted within the vessel to open and/or reinforce collapsing or partially occluded sections of the lumen.
Stents may be formed of metallic materials as well as polymeric and biodegradable materials, either in total or in part. In many procedures, polymeric or bioabsorbable prostheses are preferred over metallic devices, for example, due to the relative ease of removing a device intended for temporary implantation, or the capacity to be absorbed into the body.
When maintained in the reduced-radius state under a constant load for any appreciable length of time, a prosthesis formed of polymeric or bioabsorbable material may, however, undergo permanent or plastic deformation. When released from the catheter or other delivery device, such prosthesis may radially self expand to a diameter considerably less than its relaxed-state diameter prior to preloading. This phenomenon is commonly referred to as stress relaxation or “creep”. This phenomenon is aggravated when a polymeric or bioabsorbable prosthesis is exposed to elevated temperatures in its reduced-radius state, for example during a sterilization procedure, which may be performed prior the outset of the prosthesis deployment procedure.
To counteract this phenomenon of stress relaxation or creep, the polymeric or bioabsorbable prosthesis may be sterilized and/or stored in its relaxed state, i.e., not significantly reduced radial state, until just before it is to be used. When the physician is about to begin a procedure, he or she may load the polymeric prosthesis into the delivery system. Consequently, the prosthesis remains compressed in the reduced-radius state only for a short time, perhaps only several minutes. While such a procedure counteracts the problem of creep, the procedure is, however, more difficult and time consuming. Although it is common practice to load a stent into a sheath during assembly of a stent delivery system, such loading often involves numerous steps and often requires the use of multiple components (e.g., tools and fixtures) that are not part of the stent delivery system. For example, currently available stent delivery systems often require that a stent be loaded onto a delivery system by means of a funnel, basket or other similar device which are not part of the delivery system.
There remains a need in the art for an improved stent loading device that is permanently attached to a stent delivery system to allow loading of a stent into stent delivery systems at the time of use, while minimizing the risk of damaging the stent in the process.